NCDC added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.

Long-term moisture deficits (last 24 to 36 to 60 months) persisted across much of the West into the northern High Plains and central Plains.

Please Note: The data presented in this drought report are preliminary. Ranks, anomalies, and percent areas may change as more complete data are received and processed.

National Overview

On the national scale,

severe to extreme drought affected about 7 percent of the contiguous United States as of the end of February 2005, an increase of about 2 percent compared to last month

about 11 percent
of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of February

on a broad scale, the previous two decades (1980s and 1990s) were characterized by unusual wetness with short periods of extensive droughts, whereas the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness

about 32 percent of the contiguous U.S. fell in the severely to extremely wet categories at the end of February

a file containing the national monthly percent area severely dry and wet from 1900 to present is available

historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page in files having names that start with "drd964x" and ending with "txt" (without the quotes).

Winter (December-February) was particularly dry in the Pacific Northwest, northern Rockies to central High Plains, and Southeast. Long-term moisture deficits persisted in many areas. Much of the northern Rockies and Pacific Northwest were dry at the 6 to 24 month timescales. Many Alaska stations, especially in the interior and southern coastal regions, were drier than normal at the 12 month timescale. Severe moisture deficits were evident at the 36 to 60 month timescales across much of the West into the northern High Plains and central Plains. These long-term hydrological drought conditions are reflected in the March 1United States Drought Monitor map. Below-normal precipitation also persisted at the 60 month timescale across parts of the Southeast and extreme northeastern New England.

Streamflow levels were below seasonal norms across much of the Pacific Northwest, parts of the central and northern Rockies and Great Plains, and a few parts of the coastal Southeast, both as computed by models and based on USGS observations.

The weather pattern during February was a continuation of the pattern that has characterized the Rockies and West for much of the last 4 to 6 months. As a result, snow water content of the western mountain snowpack contrasted sharply from south to north. Basin-averaged end-of-February snowpacks in parts of Arizona, Nevada, central California and Utah were above average, while snowpacks in Oregon, Washington, Idaho, Montana and the east slopes of the northern Rockies were significantly below average. This pattern is also apparent in basin-averaged water-year-to-date precipitation anomalies. As reported by the USDA, several individual stations in the remote high altitude SNOTEL network set new record lows (in the north) and highs (in the south) for both snow water content and water-year-to-date accumulated precipitation. Many stations in the Pacific Northwest and northern Rockies shattered snow water content records set during the record dry 1976-77 winter. Snowpack conditions in Alaska were generally above normal in the interior regions, below normal in coastal areas.